This study aimed to present a novel clay/biochar composite adsorption particle, which made from abandoned reed straw and clay to remove ammonia nitrogen (NH 4 +-N) from micro-contaminated water. The removal performance of NH 4 +-N by composite adsorption particle was monitored under different raw material proportions and initial NH 4 +-N concentration. Besides, adsorption kinetics and adsorption isotherms were investigated to reveal the adsorption mechanisms. The results showed that NH 4 +-N was effectively removed under optimal proportion of biochar, foaming agent and crosslinker with 20%, 3%, and 3%, respectively. The optimal contact time was 150 min and the best removal efficiency was 88.6% at initial NH 4 +-N concentration of 20 mg L −1. The adsorption performance was well described by the second order kinetic model and Freundlich model. The novel clay/biochar composite adsorption particle in this study demonstrated a high potential for NH 4 +-N removal from surface water.